NEWSNEWSFOCUSFOCUS on March 28, 2017 The Coming Copper Peak http://science.sciencemag.org/ Production of the vital metal will top out and decline within decades, according to a new model that may hold lessons for other resources IF ELECTRONS ARE THE LIFEBLOOD OF A even if copper is more abundant than most per from the earth has always come to the Downloaded from modern economy, copper makes up its blood geologists believe. That would drive prices rescue before, he notes, so he expects a much- vessels. In cables, wires, and contacts, cop- sky-high, trigger increased recycling, delayed peak that businesses and consumers per is at the core of the electrical distribu- and force inferior substitutes for copper will comfortably accommodate by recycling tion system, from power stations to the deli- on the marketplace. more copper and using copper substitutes. cate electronics that can display this page of Predicting when production of any nat- The copper debate could foreshadow Science. A small car has 20 kilograms of ural resource will peak is fraught with un- others. The team is applying its depletion copper in everything from its starter motor certainty. Witness the running debate over model to other mineral resources, from to the radiator; hybrid cars have twice that. when world oil production will peak (Science, oil to lithium, that also face exponentially But even in the face of exponentially rising 3 February 2012, p. 522). And the early recep- escalating demands on a depleting resource. consumption—reaching 17 million metric tion of the copper forecast is mixed. The work tons in 2012—miners have for 10,000 years gives “a pretty good idea that likely we’ll get So far, so good met the world’s demand for copper. a peak somewhere around midcentury,” says The techno-optimists were right about cop- But perhaps not for much longer. A group industrial ecologist Thomas Graedel of Yale per in the past. From nearly nothing in the of resource specialists has taken the first University. Technological optimists disagree. mid-18th century, copper production soared shot at projecting how much more copper “Not that it couldn’t happen, but I don’t think along an exponential curve notched only by miners will wring from the planet. In their it’s likely to happen,” says resource econo- world wars and economic crises. That’s all model runs, described this month in the jour- mist John Tilton, research professor emeritus the more impressive considering the accom- nal Resources, Conservation and Recycling, at the Colorado School of Mines in Golden. panying decline in the richness, or grade, production peaks by about midcentury New and better technology for extracting cop- of the ore being mined. Anyone extracting a ZHIPING/COLOR CHINA PHOTO/AP IMAGES YANG CREDIT: 722 14 FEBRUARY 2014 VOL 343 SCIENCE www.sciencemag.org Published by AAAS NEWSFOCUS Headed down. Miners must move megatons of low- 30 grade copper ore at the Zijinshan mine in South China. Historical and Projected 25 Copper Production mineral resource goes for the richest, most easily mined deposits fi rst, so ore grades ran In million tons from 10% to 20% copper until late in the 19th 20 Australia Chile century and then plummeted to 2% to 3% in China FSU/Russia the early 20th century. Since the mid-1990s, Peru 15 Mexico the world copper grade has been just below USA Zambia 1% and in slow decline, according to data Rest of world compiled by resource geologist Gavin Mudd 10 of Monash University, Clayton, in Australia, in a 2013 paper in the International Journal of Sustainable Development. 5 Even though the available ores have become poorer, forcing miners to claw ever Historical Projected greater volumes of rock from kilometer- 0 deep open pit mines, the price of copper has 19001920194019601980200020202040206020802100 trended downward since 1900 (with a nota- ble spike since 2005 driven by China’s hun- Heading up, until … ger for raw materials). Multiple factors have The world has been driven the price decline. Geologists found a producing ever larger new type of copper deposit—the porphyry amounts of copper ores of buried magma formations—that is (left, in a purifying electrolytic bath), but on March 28, 2017 now the source of most of the world’s copper. given the planet’s fi nite And lately they have been fi nding extractable endowment, production porphyry copper faster than it is produced, must peak. A model pro- according to Richard Schodde of MinEx jection has production Consulting in Melbourne, Australia. Equip- peaking by 2040. ment manufacturers have built humongous shovels and dump trucks to move huge vol- umes of porphyry ore. And chemical engi- neers have developed processes such as heap leaching—trickling weak sulfuric acid higher standard of living, which today means Mohr’s model to copper. For their study, the through piled crushed ore—to get copper out a higher consumption of copper per person. group drew on a database of the extractable http://science.sciencemag.org/ (FEBRUARY 2014) © PUBLISHED BY ELSEVIER B.V.; AXEL SEIDEMANN/AP PHOTO 2014) © PUBLISHED BY ELSEVIER B.V.; (FEBRUARY of low-grade ore. Sooner or later, world copper production copper at all known mine sites that was com- 83 Even with the technology that is now will increase until demand cannot be met piled by Mudd and Weng and published in in hand—not what might be developed from much-depleted deposits. At that point, 2012. The group assumed that per capita someday—the copper now within reach of production will peak and eventually go into demand for mined copper would continue miners is considerable. At this past October’s decline—a pattern seen in the early 1970s to rise at the historical rate of 1.6% per year Geological Society of America meeting, U.S. with U.S. oil production. and that the world’s population would grow Geological Survey researchers led by geol- For any resource, the timing of the peak from today’s 7.1 billion people to 10 bil- Downloaded from ogist Jane Hammarstrom of USGS head- depends on a dynamic interplay of geology, lion in 2100. They taught the model how to quarters in Reston, Virginia, reported their economics, and technology. But resource behave realistically by fi tting it to past cop- new assessment of the porphyry copper yet modeler Steve Mohr of the University of per production for each country and type of to be discovered that could be economically Technology, Sydney (UTS), in Australia, deposit. In the model, increasing demand RESOURCES, CONSERVATION AND RECYCLING RESOURCES, CONSERVATION , mined with current technology. By inferring waded in anyway. For his 2010 disserta- elicits increased production at existing mines how much copper might be beneath geologi- tion, he developed a mathematical model for and the opening of new mines. ET AL. cally likely terrains around the world, the projecting production of mineral resources, The model delivers some good news, group estimated that 2.2 billion metric tons of taking account of expected demand and the suggesting that production can rise to meet economically extractable metal remain to be amount thought to be still in the ground. In expected demand for the next 2 to 3 decades. found. At current rates of production, that’s a concept, it is much like the Hubbert curves “It’s not a story of doom and gloom, of run- 125-year supply for the world. drawn for peak oil production, but Mohr’s ning out tomorrow,” Giurco says, “but rather model is the fi rst to be applied to other min- of needing to be more mindful of use.” But Not so fast eral resources without the assumption that trouble comes in the longer term. With the The world’s copper future is not as rosy as a supplies are unlimited. amount of extractable copper in the Mudd and minimum “125-year supply” might suggest, Now Mohr and Mudd have teamed up Weng compilation, the model shows produc- however. For one thing, any future world with resource specialists Stephen Northey of tion peaking just before 2040; after that, cop- will have more people in it, perhaps a third Australia’s national research agency CSIRO per can’t be extracted from depleted mines more by 2050. And the hope, at least, is that a in Clayton, Zhehan Weng of Monash Clay- any faster, no matter how high the price. CREDITS (TOP TO BOTTOM): ADAPTED FROM S. NORTHEY CREDITS (TOP TO BOTTOM): ADAPTED FROM S. NORTHEY larger proportion of those people will enjoy a ton, and Damien Giurco of UTS to apply Increasing the amount of accessible cop- www.sciencemag.org SCIENCE VOL 343 14 FEBRUARY 2014 723 Published by AAAS NEWSFOCUS per in the model by 50% to account for what those in the past, he says, “you can’t tell.” ares of wetlands, ponds, and lakes. might yet be discovered moves the production Furthermore, the models don’t take into As a crude way of taking account of such peak back only a few years, to about 2045. It account constraints on copper mining that social and environmental constraints on pro- just takes a lot of copper to satisfy exponen- could make things worse. “The critical issues duction, Northey and colleagues reduced tially growing demand, Mohr says. In addi- already constraining the copper industry are the amount of copper available for extrac- tional model runs performed at the request social, environmental, and economic issues,” tion in their model by 50%. Then the peak of Science, Mohr found that even doubling Mudd writes in an e-mail. Any process that came in the late 2030s falls to the early the available extractable copper pushes peak intended to extract a kilogram of metal locked 2020s, just a decade away.